The citadel began in the early nineteenth century. The original Citadel was built of earth, however, during the first decades of the nineteenth century tens of thousands of people worked on the construction of the ramparts, built in the style of French military engineer Vauban. Inside the Citadel is the Imperial city – a kind of replica of Beijing's Forbidden city.

During the war with the United States the Citadel and the Imperial city was badly damaged and one hundred and fifty buildings survived only about twenty. Partially the reconstruction and restoration of buildings, but a lot has remained in ruins.

Gate Roman lead inside the Citadel and have five inputs: Central - for the Emperor, two for the Royal elephants and another two for Royal servants-mandarins. The gate is crowned by a huge Guard tower of five phoenixes. Here in 1945, the last Emperor of the Nguyen dynasty signed the abdication.

Signal the ivory tower To dominates the southern fortifications of the Citadel. Not far from it and the gate Ngan is parade square, which has nine bronze cannons – the so-called dynastic guns. They symbolize the four seasons and five of ritual elements.